WIRELESS SYSTEM FOR MONITORING
THE USE OF SPACE IN CAPTIVE PRIMATES

Barbaro Vincenzo (*), Bartolini Pietro (*), Bernarducci Romano (*), Vitale Augusto (**)
(*) - Laboratorio di Ingegneria Biomedica
(**) - Laboratorio di Fisiopatologia, di Organo e di Sistema
Istituto Superiore di Sanità - Viale Regina Elena 299 - 00161 Rome - Italy

INTRODUCTION The analysis of the use of space by captive primates can be used to approach different behavioural issues. On one hand, for example, a differential use of the height of a cage can model a predisposition, by a particular species, to use different altitudes of the forest canopy. On the other, a captive primates could use more a certain part of the cage than another one, depending on the kind of enrichment present in that part. In the latter case, the results could be important for evaluating the psychological welfare of the subject. Unfortunately, both the continuous recording and the analysis of the data can be both partial and time-consuming. In this paper we propose an automatic system for monitoring the use of space by common marmoset (Callithrix jacchus) that can overcome both difficulties.

METHODS The system proposed here represents an integration of a system previously used to record ECG in captive primates. It is based on DATAQUEST IV (Data Sciences Inc., St. Paul, Minnesota), and it includes 16 antennas connected to eight receivers RLA2000. Ten antennas are mounted inside the receivers, whereas six of them are enclosed within a system of three orthogonal axes of perches, used by the animals for resting. The transmitter is implanted in the peritoneal cavity of the monkey and can be actived remotely in order to transmit the ECG.

Each receiver chooses the strongest signal between the two antennas and send it to the multiplexer (RMX-10). The multiplexer chooses the strongest signal between the eight receivers, and has the capability to indicate this particular receiver by means of an external module. We designed and build a replacement for such module, that converts the signals and sends them to a PC through the standard parallel port. It is expected that the strongest signal comes from the receiver to which the animal is nearest to. A software specifically designed records the data on hard-disk, where they can be later retrieved by the most common used electronic spreadsheets. It is worthy to notice that in order to use such system it is not necessary to activate the ECG recording system.

RESULTS The results have met the expectations; in fact, the system was able to precisely identify the position of the animal in relation of the 16 "zones" covered by the antennas. The considerable storing capacity of hard disk, made possible the recording of consecutive days of use of space in the cage by the monkey, without the need of human intervention. Particularly in this latter case the system, compared with a standard registration and analysis of behaviour through videotapes, has represented a considerable saving of time, without losing in accuracy.